Magnetic particle detection device having two separate movable electromagnets and aninterfitting bar member for magnetically coupling the cores of same



Jan. 26, 1965 M. PEVAR 3,167,708

MAGNETIC PARTICLE DETECTION DEVICE HAVING TWO SEPARATE MOVABLE ELECTROMAGNETS AND AN INTERFIT'IING BAR MEMBER FOR MAGNETICALLY COUPLING THE CORES OF SAME Filed July 12, 1962 F-|s M ZNVENTOR Maxwell PQVCII.

AGENT United States Patent 3,167,708 MAGNETIC PARTICLE DETECTION DEVICE HAV- ING TWO SEPARATE MOVABLE ELECTROMAG- NETS AND AN INTERFITTIN G BAR MEMBER FOR MAGNETICALLY COUPLING THE CORES 0F SAME Maxwell Pevar, 8116 Fayette St., Philadelphia, Pa. Filed July 12, 1962, Ser. No. 209,464 1 Claim. (Cl. 32438) The invention relates to a magnetizer for the wellknown nondestructive inspection or testing of workpieces by means of magnetic particles. This type of inspection is widely used for finding faults, flaws or other inhomogeneities or for determining the quality of welds, castings, forgings, etc. More specifically, the invention relates to a magnetizer for nondestructive inspection or testing of workpieces by means of magnetic particles,

Among the objects of the invention are the improvement of the magnetizer in regard to its adaptability to different shapes of workpieces, the improvement of the transfer of the magnetic flux from the magnetizer to the workpiece, the improvement of the portability of the magnetizer, improvement of the versatility in general and other improvements.

The objects of the invention are mainly achieved by two novel individual magnets, each having its own electrical winding and a core with a workpiece-engaging end and the other end remote from the workpiece-engaging end, the windings and the current supply for them being adapted for inducing opposite magnetic polarity in the workpiece-engaging ends of the two magnets of one pair, by the formation of openings in the other ends of the cores, and by a bar-like member of magnetically conductive material of such constant cross-sectional shape and dimensions as to slidingly fit into said openings for closing the magnetic circuit between the cores while permitting adjustment of the distance between both magnets without changing their angular position relative to each other, and whereby said member may be pulled out of said cores so as to permit independent handling and movement of each of said magnets.

The aforesaid and other objects and features of the invention as well as specific details thereof will be more fully disclosed by the following description of one embodiment of the invention and by the illustration thereof in the attached drawing.

In the drawing:

FIG. 1 is a view of a pair of electro-magnets connected to a power pack;

FIG. 2 is a wiring diagram of a pair of electro-magnets and of the power pack;

FIG. 3 is a section through the windings of one of the electro-magnets and an elevation of the core thereof; and

FIGS. 4 and 5 are views of two different alternative arrangements of a pair of electro-magnets.

The two electro-magnets and 11 of a pair are connected to power pack 12 by a cable harness 13. The power pack 12 is connected by three-pole plug and receptacle 14 and cable 15 to a source of alternating current (not shown).

One of the poles of plug 14, the pole 16, serves as ground and is connected by conductor 17 to one pole 18 of a receptacle 19 provided on the power pack.

A three-position switch has switching elements 21. In one position of the elements 21, the position shown in full lines in FIG. 2, the current is shut off.

In a second position, the position shown by dotted lines in which the elements 21 extend in the diagram to the right, the current source is connected to poles 22, 23 of receptacle 19 over variable A.C.-output autotransformer "ice 24, transformer 25 and rectifier 26 in simultaneously lighting a white signal bulb 27. This is the magnetizing position.

In the third postion, the position also shown by dotted lines in which the elements 21 stand in the diagram to the left, the current source is connected to the poles 22, 23 of receptacle 19 over the variable autotransformer 24, in lay-passing rectifier 26, in simultaneously lighting red signal bulb 28. This is the demagnetizing position of switch 20.

Plug 29 of cable harness 13 is adapted to matingly engage receptacle 19 of power pack 12 and has poles 3t), 31 and 32 which latter make contact with poles 18, 22, and 23, respectively, of receptacle 19. Wires 33 connect ground pole 30 to poles 34 of two, preferably smaller plugs 35 and 36 which are adapted to engage receptacles 37 and 38, respectively, of the magnets 10 and 11.

Poles 31 and 32 are connected by wires 39 and 40 to oppositely oriented poles 41/44 and 42/43, respectively, of plugs 35 and 36.

Upon plugging plugs 35/ 36 into the receptacles 37/38, poles 34, 41, 42 will make contact with poles 45, 46 and 47 of receptacle 37 and poles 34, 43, 44 with poles 45, 48, 49 of receptacle 38. As is evident, D.-C. current fed from power pack 12 will eventually flow in opposite directions through the windings or coils 50 and 51 of the two mating magnets 10 and 11 and cause opposite magnetic polarity. Even though the coils 50 and 51 are wound in the same direction, this required opposite polarity is achieved by the wiring of the connecting cables and plugs and by the use of plugs permitting of but one plug-in position.

Each magnet, as visible from FIG. 3, has a bar-type core 52 surrounded by coil 50. The core 52 has the general shape of a rectangular parallelepiped, and encloses an opening 53 so as to present a handle 54 and is composed of laminations 55 preferably extending in the direction of the large surfaces of the coil. Expressed differently, the core is thin in one direction, as compared with its dimensions in the other two directions extending perpendicular to the first direction and to each other. The opening 53 extends through the core 52 in the direction of its thin dimension. The surface 56 at the end opposite opening 53 and handle 54 presents the workengaging end. This end may be fitted with shoes or adapters (not shown) to accommodate different shapes, e.g. tubular, of workpiece surfaces. Rather than forming the handle as part of the core, it also may constitute a separate element.

In FIG. 1 the magnets Iii/11 are positioned on opposite sides of a Weld seam 57 of workpiece 58.

In FIG. 4 the magnets are attached to webs 59 and 69, respectively, of a beam structure 61 and serve for inspecting seam 62 between the webs.

In FIG. 5 a preferably laminated, bar-like member of magnetizable or magnetically conductive material or core 63 extends through the openings 53 of the electro-magnets so as to complete the magnetic circuit, or member 63 may present a workpiece to be inspected. The connecting core 63 may take a variety of shapes or may be flexible so as to adapt itself to dilferent relative positions of the electro-magnets 10/11. Of course, member 63 has, as illustrated, cross-sectional shape and dimensions corresponding to those of the openings 53 so that it may be slid into or taken out of the openings and does not offer any appreciable resistance to changing the spacing be tween the magnets.

For demagnetizing the switch 20 is placed in the position delivering A.-C. current to the magnets 10 and 11 and the variable autotransformer 24 is turned back to zero.

The invention is not restricted to the described and illustrated embodiment or the details thereof but is susceptible to modifications and adaptations which will easily occur to those skilled in the art. I What is claimed is:

Magnetizer for nondestructive inspection or testing of workpieces by means of magnetic particles, the magnetizer comprising: two separate, relative to one another movable magnets, each magnet having a core surrounded by an induction coil; said cores each having a workpieceengaging surface at one end; means for connecting the coils of both magnets to a source of electric current, said connecting means and the directions of the windings of both coils being such as to insure opposite magnetic polarity of said workpiece-engaging surfaces of both magnets; each of said cores being thin in one direction transversely to the axis of the coil surrounding it compared with its dimensions in the other two directions perpendicular to said one direction and to each other; a oar-like member of magnetically conductive material and of constant crosssectional shape and dimensions; the other end of each core extending beyond said coil and providing an opening completely through the core in the direction of its thin dimension and mating in shape and dimensions to the cross-section of said bar-like member so as to permit said member to be inserted into and slide in the openings of both cores thereby closing the magnetic circuit between the cores while permitting adjustment of the distance between both magnets without changing their angular position relative to each other, and whereby said bar-like member may be pulled out of said cores so as to permit independent handling and movement of each of said magnets.

References Cited in the file of this patent UNITED STATES PATENTS 454,090 Thomson June 16, 1891 2,352,371 Clarke June 27, 1944 2,602,097 Muller July 1, 1952 2,832,922 Deforest Apr. 29, 1958 2,848,748 Crump Aug. 26, 1958 FOREIGN PATENTS 786,141 France June 3, 1935 

